The Karate Kid (1984) - 5 major mistakes

Revealing: When Daniel is about to paint the fence of Mr. Miyagi, Mr. Miyagi tries to catch a fly with chopsticks. Daniel tries as well. You can see pretty clearly that the "fly" is attached to a wire or a nylon string, moving like a pendulum and bounces as if someone's pulling the string.

Continuity: We first see from the inside of the door (and therefore backwards) the instructions that Mr. Miyagi leaves for Daniel to paint the house. In the next shot we see the same note from the outside - from Daniel's viewpoint. Clearly they are two different notes. The left & right arrows switch directions, the drawings of the hands change, the position of Miyagi's signature changes, and the placement of some of the exclamation points changes.

Revealing: When Daniel is running from Johnny and his gang after the bathroom incident at the dance, there's a lot of fog outside. If you look at one of the trees in the background, you can see that all the fog is being puffed out from behind the tree - obviously a fog machine.

Other: In the semi-final where John Lawrence fights against Darryl Vidal, the female referee has major problems of what to do. When Lawrence gets his first point, the referee first raises her red flag (Vidal is wearing the red ribbon) but then swiftly changes her mind. And when Lawrence gets his third point, the female referee again incorrectly raises her red flag.

Continuity: In the final fight between Daniel and Johnny, there is a time when Johnny's head band falls off (after Johnny scores his second point). Right after it falls off, if you look quickly you can see it back on, then it goes back off.